24' Diameter Parachute Canopy

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24' Diameter Parachute Canopy

Postby MistaBiggs » Tue Jan 27, 2004 8:39 am

Does anyone have plans for a 24' Diameter Parachute Canopy that has been tried / tested / and successful?

I'm a newbie (well will be this year) and I'm not exactly 100% what the conditions will be like in BRC (having never experienced it firsthand). I read several posts and articles, but I still feel very uncertain about many things.

I'm planning on buying a 24' diameter parachute and building a shade canopy to pitch a tent or two under.

I'm not very mechanically inclined ... but just about everyone I know (close friends) are. So, I could easily get help "prepping" for construction. I just don't want to show up at BM with inadequate materials. At the same time ... I don't want to "over do it" either.

Any help and / or suggestions would be GR8T!!!

Thanks in advance!!
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Postby robotland » Tue Jan 27, 2004 9:54 am

There have been many posts about 'chutes in the past- try checking the archived discussions, or, hell, just ask Bob.....
I'm more of a dome guy, myself, but I know that 'chutes are better at catching and holding wind than shedding it, and even the green ones aren't thick enough to darken it up underneath. Still, you can adapt them in clever ways, as many do. Anchored securely, but given "flow room", and with wind vents cut into them and hemmed against fraying, they are flexible and extra easy to pack....I'm playing with an "umbrella" design with a small cargo 'chute and fiberglass bikeflag poles mounted on a metal hub- results to come......
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Postby MistaBiggs » Tue Jan 27, 2004 10:00 am

It could be a dome ... as it is already circular. I just need ideas on getting the shade shelter up and keeping it up (in the worst storms BRC has to offer).

I'm not dead set on anything. I'm just looking into it ... as from what I've read ... it is (somewhat) of a necessity.
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nonagon

Postby Playa Paul » Wed Jan 28, 2004 10:56 pm

the parachute solves a lot of issues yet creates brand new ones too. the size(24') is deceptive due the multiple dimensions inherent in chutes. the typical military green chutes are stitched to be quite round. they catch wind, don't give 100% shade, but make less noise than tarp.

you'll also find that your design becomes based on a synergy bewteen the chute and the structure. the usual suspect structure's do little to alter the chute taking advantage of it manufactured symmetry... build a dome, drape it over ... put up a pole, stake it out ... stretch it out over the camp ... make a frame, tie it on ... etc.

the structure can be a lot of materials, choose something sturdy. shape, size and architecture are limited by those materials and how you use the chute. you should know how you want to put things together, connections in the structure, stakiing it to the ground, applying the chute, etc. build prototypes considering the playa's harsh conditions(not just your locataions). your design may evolve as you find limitations, keep reciepts.

our design criterea was simply no center pole with a full feild of vision. we tried to fill a chute with a rasied pvc dome, like a mushroom, but that was way to flimsy. we went with an metal conduit circus-tent-like octogon skeleton held together with bolts, nuts, washers and couplers. the chute was stretched out on the top which was shaped like spokes of a wheel.
the final evolution came when the chute was still too loose and another side was added, thus was born the nonagon.
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Postby robotland » Thu Jan 29, 2004 7:25 am

I've found that little spring clamps can be very handy for adjusting your shade, holding back flaps, etc.. Don't depend on them to hold in a wind gust, though- always tie down, use zip strips or such.
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Postby MistaBiggs » Thu Jan 29, 2004 8:17 am

Thanks for the replies!

Any further info or suggestions ... please post.

(I'm begining to think this is well over my head).
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Postby robotland » Thu Jan 29, 2004 9:17 am

If you might make your structure a dome, let me tell you that even though you earlier confessed to a dearth of mechanical inclination you can still pull off a dome with a little help and a coupla tools....it is VERY satisfying to assemble something on the playa that you've dragged cross-country, especially those last few bolts that suddenly solidify the frame and turn it from a pile of tubes into a "spaceage enclosure". A dome frame also offers a great number of crossbars on which to fasten your covering, making it very versatile. Unlike most canopies, they're strong enough to climb on or hang hammocks. (If you haven't tried sleeping in a big cotton Brazilian hammock, you're missing something!)
The cargo space required is roughly equivalent (for, say, a 2V 20' dome) to what a couple of golf bags would take up- you could even take a dome kit on most domestic flights!
I would be glad to assist with any specs/tips should you choose this path- There are also MANY sources of good info, starting here:

http://www.desertdomes.com/dome.html

Hurry up! You have plenty of time.
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Postby MistaBiggs » Thu Jan 29, 2004 10:50 am

THANKS!!!!

I really appreciate your tips / suggestions...

I would love to build a dome and I don't mind spending the necessary money to 'make it work'. A friend and I (both newbies) will be driving up this year (from Baton Rouge, Louisiana). We will be in his Dodge pickup truck. So, we should be able to make room for what ever we need. I just have no clue on what is required to 'pull it off' -- mainly due to we have no where near 85 mph winds around here. So, I'm kind of in the dark. I will review the link posted above (THANKS!!!). Also, feel free to e-mail me with any and all the help you can give (I'll need it -- no matter how little / much).

THANKS AGAIN!!!

(Now I'm getting a little excited ... anxious more like it).
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Postby robotland » Thu Jan 29, 2004 12:41 pm

...if you think you're excited NOW, just wait until you get to BRC and start seeing the amazing structures that people come up with first hand.....Year Two is the Year of the Edifice Complex! Even though we'll have to fly out this year, I still want to bring a dome in my luggage!!
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Postby MistaBiggs » Thu Jan 29, 2004 1:21 pm

Can you give me a rough estimate of how much $ it costs to build a 2V Dome? It'll be a 12' Radius. Just curious ...
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2v dome cost estimate

Postby dman » Thu Jan 29, 2004 5:03 pm

Hmmm, a 12' radius 2v dome implies strut lengths of 88.99 (x35) and 78.70 (x30) inches (thanks Tara!).

I haven't actually built a 2v dome so can't comment on the structural strength of struts this long in various diameters, but my intuitiion says that 3/4 inch conduit might be a bit thin for those lengths, but 1 inch should be OK (your actual mileage may vary). Certainly, using 3/4 inch conduit would mean not hanging anything of much weight from either the vertices or (goodness, no!) the middle of the struts.

3/4 inch conduit is around $2.25 from Home Depot. 1 inch conduit is $3.75 the last time I checked (couple of weeks back).

Choosing strut lengths that don't in some way add up to around 120 inches (the length of conduit from places like HD) means you will need 65 pieces, plus a few spares; 70 is a good number. So, approximately $157.50 plus tax for 3/4 inch struts, or $262.50 for 1 inch. Just remember, with this approach you are going to have 70 shorter pieces of conduit left over.

In all honesty, for the size dome you want I recommend a 5/8 3v dome built with a 142 inch radius, which means the struts work out really well, so you only end up needing about 85-90 pieces of conduit, and they can all be 3/4 inch with fewer structural worries (you still won't be able to climb on it if you weigh anywhere near what I do, but you will be able to hang hammocks & such from the vertices). Plus, the walls will be much straighter for the first few feet meaning all the space is useable, and the ceiling is higher giving more room for hot air to rise. So, for basically less than you would pay for 1 inch conduit in a 2v dome (but a bit more in other materials and labor, see below) you can have a dome that is "much better" (IMHO <g>).

Then there are bolts; for a 2v it looks like you will need 26 - 3/8 x 2.5 inch bolts, 52 washers, and 26 nuts. At that number they are probably almost cheaper in boxes of 50 than buying them individually. I use Grade 8, which is structurally overkill, but the threads don't get dinged as easily. Can't remember off the top of my head what a box of 50 grade 8 2.5x3/8 goes for, but figure on $0.20 apiece in bulk or $0.30 apiece separately, or about $10 for the bolts, and I am guessing $0.05 per washer, or $5.00 for 100, and $0.10 per nut, or $5 for 50. So, about $20-$25 in nuts & bolts. Using Grade 5 will lower that substantially, to maybe $15 or less.

For a 3v 5/8 you will need 61 bolt assemblies.

Next is rebar. I use 2 foot sections from Orchard Supply, or you can buy longer pieces and cut them (especially if you use a cutoff wheel, see below). Can't remember how much rebar is these days, but figure on $1 a foot for 1/2 inch, and you will need 10 pieces for a 2v dome, or 15 for a 3v, or $20 to $30.

Then there is paint to keep the ends from rusting once you cut & drill them. Using different colors for the different length struts really helps. I use iindustrial Rustoleum in flat colors, about $5 per can from HD, and one can will be plenty for several builds of your dome (you will want to respray the ends upon dissassembly each time because they get all scratched up no matter how careful you are). So, $10 in paint for a 2v dome or $15 for a 3v.

Then there are construction tools that you might not already have, like:

Pipe cutter, anywhere from $7 for a cheap one you probably won't like to $35 for a Rigid that you will like, but probably can't really justify for this many cuts. Plus, using a pipe cutter is a pain in the shoulder after awhile. I personally gave up on using a pipe cutter and now solely use a cutoff wheel on my 7 1/2 inch circular saw. Lots of sparks, but one $3 wheel will cut hundreds of pipes & rebar if you are careful and don't wreck the blade.

Next is something to flatten the ends. I use this on my workbench:

http://www.harborfreight.com/cpi/ctaf/D ... umber=4711

It works great and the press plates last for a few hundred presses. Cost is $70 plus tax & handling.

Then you will need to drill those holes. I think a drill press is well justified for this task, even if you go cheaper on the other tools, because getting the strut lengths just right really helps make the assembly go smoother. A decent drill press can be had for under $100. Here is one that should do the trick:

http://www.harborfreight.com/cpi/ctaf/D ... mber=44836

You will need a couple of C-clamps or a vise or two to make a jig and secure the poles during drilling. You probably have those laying around.

For drill bits I swear by 7/16 inch 135 degree cobalt and lots of cutting oil (after screwing up a titanium nitride bit and the first cobalt bit learning how to work a drill press properly). Harbor sells sets of cobalt bits, but I do not know of their quality. I buy mine from a local specialty outlet for $15 apiece and one bit is good for several hundred holes as long as you drill slowly, use lots of cutting oil and let the drill bit cut the conduit rather than just heating it up and boring through (this latter will wreck the bit after a hundred holes or so; you can still drill, but you are basically heating and punching rather than drilling at that point, and it takes longer; I am one of those obsessive types who counts time while waiting for completion; any shorter than 50 seconds per hole and I am drilling too fast; any longer than 60 seconds and the bit has gone dull). One of the items on my list is a bit sharpener, but the good ones are pricey.

Next, I use a benchtop grinder with a medium grain wheel and a wire buffer wheel to grind off any drill flash and smooth/round the ends a bit. Here's one that should do the trick:

http://www.harborfreight.com/cpi/ctaf/D ... mber=37822

And 6 inch buffer wheels are about $7 at Home Despot.

Oh, and you'll need some 9/16 inch sockets & wrenches to do the assembly. You probably have those. And a 10 inch Vise Grip (about $10) or two will come in handy. And maybe a sledge (4 lb is good, $9) to pound the rebar. And some rope to bundle up the struts and lash the rebar and what not; maybe $10 worth of 1/4 inch nylon.

So, there are some base numbers based on current prices (as of January, 2004). You can probably take it from there. And there are lots of sites that discuss dome design and fabrication. The best, IMHO, is Tara's site, at:

http://www.desertdomes.com

Oh, fab time. It takes me approximately 10 minutes per pole to do the cutting, flattening, drilling, grinding, bending and painting, on average. So figure on around 12 hours for a 2v dome and 25-30 hours for a 3v dome, assuming you excel at switching between thinking tasks and drone type tasks easily.

All the Best,

D (aka Usually Harmless)
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Postby MistaBiggs » Thu Jan 29, 2004 6:05 pm

WOW!!

I really appreciate all the info guys / girls!!

I can't wait to see one up in person!

Thanks and any additional info / tips / cautions / etc. -- keep them coming.
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Postby robotland » Fri Jan 30, 2004 6:40 am

I think Dman did a more thorough job than I could have of breaking it down-Well Done! If you have to go beyond 20', 3V probably IS the way to go, primarily because you don't want any struts to be over 5' if you want them to stay straight. Without wasting time with excessive cuts and maximizing the lengths available from a 10' stick of conduit, a 2V dome comes in under 20' diameter. I disagree regarding necessary conduit size, though- I've got a 6' dome sitting on a 12' dome sitting on a 20' dome, all 2V, all 3/4" conduit, and the dang thing's ROCK SOLID, even with ten people up on the deck! With any dome you'll want to avoid stepping on the center of a strut, and even a 1" strut will bend under MY weight, but the VERTICES should hold Mucho weight. One deck in my first dome hung by chains from the top five and polar vertices alone, and a baby elephant would have slept calmly thereupon!
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Silver Tarps...

Postby MistaBiggs » Mon Feb 02, 2004 11:38 am

Alright guys ... I'm going with the 3v 5/8 Dome structure.

However, I've decided against the parachute canopy and I'm currenlty looking into getting silver tarps to shingle the dome.

Any suggestions for suppliers?

I've found some at http://www.tarpsplus.com/greytarps.html.

However, any idea as to how much / many I'll need. They have several packages ... and I don't want to purchase to little nor to much.

Also, is 12 mil thick / durable enough?

Any help would be appreciated.

Thanks in advance!
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Silver Tarps...

Postby dman » Mon Feb 02, 2004 12:27 pm

OK, my $0.02:

1) I went with white, but lots of folks recommend silver. I haven't done any real study of one vs the other, but here is a link to someone recommending white after some study (admittedly limited and perhaps biased; this guy does sell tarps for a living, so YMMV):

http://hayandforage.com/ar/farming_ligh ... s_protect/

2) I didn't find any beginning prices lower than Tarpsplus, but watch out on the shipping. The net price after shipping may be lower from other places. The Berryessa flea market in San Jose, CA (near me) has a tarp vendor that is fairly reasonable and has the same tarps as Tarpsplus. There may be a place like that near you.

3) As for the amount of tarp needed, that depends on how you want to make the covering. You can calculate the surface area of your dome by adding up the areas of the underlying triangles. If you use a diagram like this:

http://www.desertdomes.com/pics/dome/3vdiagram2.gif (Thanks Tara!)

You can see that there are 30 "AAB" triangles and 75 "CCB" triangles. Then, you can use a site like this:

http://www.mste.uiuc.edu/dildine/heron/triarea.html (Thanks James!)

to calculate the area for the dome you are building. You might want to check the "Domes in the Default World" thread for my comments on making a covering.

4) I can't comment on the long term durability of the heavy duty tarp from Tarpsplus under playa conditions. It looks to be durable enough to last longer than a few BM like events and has held up well to my tests so far (except for heat & fire; tarp is not good around these things <g>); perhaps others can comment further.
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Postby robotland » Mon Feb 02, 2004 12:57 pm

Last year our structure was all silver tarped- to cover the base-dome (about 20' dia.) I needed two 6'x20' for the base and the equivalent of five 6'x10' for the sides. (I cut trapezoidal pieces that fit with a little overlap, and then tarptaped and grommeted them.) The top pentagon was left open, as it connected to another dome on top.....We kept a standby tarp to pull over the opening, in case of rain or dust.
In my experience, the larger the area of the tarp the costlier it is. You certainly don't want to get a single hugeass tarp and cover the dome with it, because you'd have all kinds of surplus folds. And it would have the same problem that parachutes have, that it catches wind instead of venting it. Tarps in the 6' to 10' by 10' to 20' range shouldn't cost more than five to twenty bucks or so. If silver tarps seem to be the same price as blue, check the thickness. They oughta be NOTICEABLY thicker.
Pick up a grommet kit and add extra anchorpoints where they'll coincide with the structure. Fasten with zipstrips, or ropes/bungees where you'll be adjusting the tarps for airflow or shade. Lightweight nylon cord can be zigzagged between the bottom grommets of the siding-tarps and the base of the dome frame, to limit "ballooning"caused by wind gusts.
I haven't tried this on a big scale yet, but you could experiment with holding the tarps down with a web of rope....
I recommend building the dome and then buying a couple of tarps and playing with them- That's how I figured out how to cover ours, and I discovered some ways and hindrances that hadn't come out on paper.
Also remember to check the CUT SIZE of the tarp- they'll list the dimensions BEFORE it's hemmed and grommeted, and then the cut size, usually in smaller print....(why they don't just tell you how big the damn thing is, is beyond me.)
WAIT! THERE"S MORE!
Tarps will start to fray eventually, since although they look like sheet plastic from a distance they're really woven from flat plastic "yarn". You can hem them with duct tape, although the playa heat does nasty, sticky things to good ol' "Indiana Chrome".....there's a tape called "tarp tape" that sticks pretty well and can be "cured" with heat to strengthen the bond. I use a hand torch, but be sure to keep it moving so you don't melt everything! I fold twice, about 2" each time, tape, heat, add grommets, done! Sounds like a lot of work, but it is. The results look pretty slick, though. Once I got a system going, I made individual triangle panels for most of the top structure, and we played around with shade configurations onsite. We were also able to significantly adjust the airflow by changing the covered/uncovered sections in harmony with prevailing winds.
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Postby MistaBiggs » Tue Feb 03, 2004 2:58 pm

Considering a 3v 5/8 Dome w/a 12' radius (A = 4.183, B = 4.842, & C = 4.948) ... I'm coming up with a total area of 1,031.298 -- does this seem correct?

Which would me roughly 11 (10x10) tarps. But, how much room for overlapping (shingling) should I allow -- perhaps get 12-13 (10x10's)?
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Postby Badger » Tue Feb 03, 2004 3:24 pm

Sounds about right. Some quick down and dirties for dome calculations:

Pi =3.1416 d=diameter r=radius

Circumference of circle (or perimeter) = Pi*d or Pi*2*r
Area of circle (or square footage) = Pi*r*r
Area of hemisphere (half dome for skin or roofing)=2*Pi*r*r

But you probably knew that...
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Postby robotland » Thu Feb 05, 2004 8:24 am

I try to allow for about a foot of overlap everywhere I'm trying to keep the dust out, and cut to exact size or a hair smaller for shade panels so the wind can move around them and a little light gets through. I find it easier to zipstrip a panel that is just big enough to cover the triangle, hexagon or whatever without overlapping the centerline of the strut. With my vernacular approach to geometry that also means colorcoding the tarps, since "results may vary".....
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